Water Softening.—The water softeners available on the market are numerous, and as each possesses special advantages of its own, it would be almost invidious to select any one for particular notice.
They are based upon the principle of mixing chemicals with the water to be treated, so as to precipitate the matters in solution and give a boiler feed-water free from carbonates and sulphates of lime and magnesia. The chemicals are added in the form of solutions of carefully regulated strength to the water, which flow in a continuous stream into a tank. The flow of the water and chemical reagent is adjusted by previous analysis.
The various machines differ in details of construction, and in the methods by which the mixing of the water and reagents is effected. The object to be achieved is the complete precipitation of the dissolved salts and the production of a clear water, free from sediment, in an apparatus that will treat a maximum quantity of water at a cheap rate per 1,000 gallons.
The process needs proper attention. The addition of reagents in wrong proportions will do more harm than good, and possibly result in hardening the water instead of softening it. The following may be quoted as an example:—
| Composition of Water. | Before Treatment. | After Treatment. | Change. | |
| Calcium carbonate | 13·863 | 38·920 | 25·057 | gain |
| Calcium oxide (lime) | 0·000 | 14·300 | 14·300 | „ |
| Calcium silicate | 2·062 | 3·591 | 1·529 | „ |
| Calcium sulphate | 1·625 | 2·121 | 0·496 | „ |
| Magnesia | 0·000 | 0·266 | 0·266 | „ |
| Ferric oxide, etc. | 0·447 | 0·987 | 0·540 | „ |
| Scale forming mineral | 17·997 | 60·185 | 42·188 | gain |
| Calcium chloride | 1·331 | 2·114 | 0·783 | gain |
| Magnesium chloride | 0·672 | 0·000 | 0·672 | loss |
| Sodium chloride | 0·478 | 0·476 | 0·003 | „ |
| Soluble salts | 2·482 | 2·590 | 0·108 | gain |
| Total mineral matter | 20·479 | 62·776 | 42·297 | gain |
| Carbonic acid gas | 9·71 | 0·000 | 9·71 | loss |
| Oxygen gas | 0·66 | 0·66 | 0·000 | „ |
Treatment required: 1·8 lbs. of lime, 0·2 lbs. soda ash per 1,000 gallons. Apparently 5·5 lbs. of lime were being used and no soda (Stromeyer).
Superheated Steam.—The effective application of the energy of the high pressure steam is probably one of the most important problems in paper mill economy. The use of superheated steam is being extended in every direction, and, in addition to the advantages obtained in the steam engine itself, its wider possibilities for the boiling of esparto, wood, and fibres generally have been noted. The following case may be quoted as the result of a trial at a paper mill, showing for stated conditions the advantages of superheated steam:—
| — | Superheated Steam. | Ordinary Steam. |
| Duration of test hours | 26·00 | 34·00 |
| Coal consumed (lbs.)— | ||
| Per hour | 610·50 | 661·50 |
| Per 1 h.-p. hour | 1·83 | 2·08 |
| Water evaporated (lbs.)— | ||
| Per hour | 4,832·00 | 5,679·00 |
| Per 1 h.-p. hour | 14·55 | 17·80 |
| From and at 212° F. | 8·70 | 8·94 |
| Steam, temperature F. | 464·00 | 334·00 |
| Pressure | 90·30 | 90·80 |
| Steam engine— | ||
| 1 h.-p. total | 331·50 | 323·20 |
| Temperature F. | 381·80 | 333·80 |
| Coal used per 1 h.-p.— | ||
| Per hour at boiler | 1·83 | 2·08 |
This appears to show a saving of 12 per cent.